Modern Vespa

Part 4 – Installing the Polini Upgear Kit


One of the complaints often heard from those who have installed the Malossi 190 cylinder kit is that – although it dramatically increases torque to allow for quicker acceleration – it does not allow significantly higher top speeds because of engine rpm limitations. In an effort to make my LX more versatile by improving all aspects of its performance – including top end – I figured I could exploit some of that increased torque to increase top speed significantly by going to taller final gearing while I had the engine out of the bike anyway. To that end, I installed the Polini upgear kit.

A word of caution. If you are not installing a cylinder kit to significantly increase your torque, don’t waste your money on the upgear kit. Installing it with the stock engine will only decrease your acceleration capability and may actually reduce your top speed, as the stock engine won’t produce enough horsepower to exploit the taller gearing.

Although I did the upgear kit installation at the same time as I installed the cylinder kit, you don’t have to. It can be done with the engine still in the scooter. You’ll need to remove the exhaust system and rear wheel, as well as the transmission cover and clutch assembly to get at the final drive parts, but that is all that is necessary.

With the engine out of the scooter and the transmission cooling duct and airbox already out of the way, removing the transmission cover involves only removing the driven (clutch) shaft nut and the perimeter screws. To loosen the driven shaft nut, it is necessary to immobilize the clutch assembly with a clutch holding tool. Once the transmission cover is off, simply slide the clutch assembly off its shaft and set it aside.

The first step in actually installing the upgear kit is to drain the gearbox oil:


Remove the brake shoes by folding them outward toward each other and pulling them free of the actuating cam and pivot pin (note that the brake shoes have to come off, as one of the cap screws holding the gearbox cover on is beneath the upper shoe):


I removed the brake lever and cam to lubricate them, but I guess that wouldn’t really be necessary just to install the kit:


To open up the gearbox, remove the cap screws securing the cover:


… and carefully slide the cover off. The intermediate gear shaft and rear axle shaft/gear will come free with the cover:


Remove the intermediate gear shaft:


The larger spur gear on this shaft will need to be pressed off at a machine shop with a large-capacity hydraulic press and replaced with the one that comes with the upgear kit. Forget about trying to use a simple arbor press or heating/cooling methods as this is a really tight interference fit. A big press is necessary, so go straight to a machine shop. I paid $20 to have the old gear pressed off and the new one pressed on while I waited.

Slide out the driven shaft, taking extreme care not to damage the oil seal as you remove the shaft:



Once you are back from the machine shop, insert the new driven shaft with its slightly larger gear that comes with the kit (again with care not to damage the seal), and insert the intermediate shaft with its newly installed spur gear:


Apply some gear oil to the gears and reinstall the gearbox cover:


Torque the cover screws to spec… and don’t make fun of my ancient beam-type torque wrench that served me well for over 40 years (I’ve since replaced it with a modern “click” type):


Refill the gearbox with the specified amount of gear oil. Before replacing the clutch assembly and tranny cover, give the driven shaft a spin with your fingers to make sure everything turns smoothly:


That’s it for the actual upgear kit installation. In Part 5, I’ll talk about variator tuning to get the most out of the engine and gearing mods.

Last edited by Silver Streak on Mon Feb 15, 2010 6:05 pm; edited 1 time in total

Great job again thank you for taking the time to put it all out there for us. This winter has been bad for PA and I think I will do my gear kit now that I have the engine out and in the basement. The job looks like it will be real easy. Did the gear set come with a new gasket for case? Did you use an sealer on the case? Thanks again I have been checking everyday to see if you have added your next report and I love the classic torque wrench.
Chris

Thanks.

No, there was no gasket included in the kit. The case came apart cleanly, so there was no reason not to reuse the old gasket. I didn't use any gasket compound, and it sealed up fine... no leaks.

Once you accept the fact that you'll have to rely on a machine shop for the gear pressing, the installation is dead easy.

Yeah, the weather has been hell here too. Still over a foot of snowpack on the ground, and a lot of the back roads still are not clear. Don't know when I'll be able to get back to the variator tuning.

This has really been a bang up prodject and your doing an excelent jpb of it. Thanks

Why didn't you use the Malossi upgear kit instead of the Polini.

I have the 190cc kit and Malossi gear kit.

It was what was readily available, it was on sale at a considerable discount, and I've had better luck historically with Polini aftermarket products than Malossi.

You've got much better access to a broad selection of aftermarket scooter performance parts over there in Europe than we do here Stateside.

They have a e-shop now. Check there site.

Your tutorials are awesome....can't wait for them to be continued and to do those mods on my own scoot

I heard that the Polini transmission is longer than the Malossi, correct?

The Malossi gear kit is actually a down gear when used on the 150. Malossi kit M6711860 has 16/42 tooth counts and is taller than the 15/42 of the LX125 but shorter than the 16/41 of the LX150

Gear tooth counts and interchangeability

Thanks for the contribution oopsclunkthud but I am even more confused now

So what is the longest gearing to be used on a 190/200cc Vespa LX?

To my knowledge, the longer the gearing is, the more top speed you can gain.

The tallest gearing on the LX is exactly what Silver Streak has used. The Polini 17/44 Primary gear kit with the LX150 secondary gears. With the variator maxed out it should hit max power at 77mph and the revlimiter at ~88mph.

OK thank you

I have a LX125. Do LX125 and LX150 have the same secondary stock gearing or would I have to change those too?

what about the fuel injected models like the lx125ie?
will those upgear kits work?

Yes, no difference in final drive.

Not with with stock displacement though, 190 kit only.

many thanks!

yes, I also have the 190kit to install

Even with the 190 kit, you are unlikely to have enough horsepower to quite get to the power peak with the Polini gearing maxed out, to say nothing of hitting the rev limiter. My bike tops out at 75 (120kph) indicated on the level without a tailwind.

Perhaps, if you are small and your scooter has good aerodynamics, you might hit the 77 mph power peak.

well that's already pretty good!
i'm also going to install a j.costa variator and the malossi forcemaster 2!

Yeah, think Polini gearset is slightly "tall" for the US 150. Euro 125 has lower secondary ratio so overall ratio is lower with the Polini.

Mine with lower ratio GT secondary will see 78 indicated in a tuck, 80 with a tailwind.

I agree completely with that assessment. Mine -- in its present state -- is geared a bit too tall for maximum top speed potential, and I had to compensate with extensive variator tuning to preserve good off-the-line performance.

Oh well, I was optimizing it to be a touring bike, and I guess my gearing reduces wear at cruise. I'm still looking for ways to boost the horsepower a bit (hot cam?, 3-valve head?). If I can eek out just a bit more raw power, my gearing will probably be optimal.

Recently discoverd this thread as part of the series and very interested as it is covering the exact upgrades i am planning for my ET4 125!

Does anyone know if Part 5 was ever posted - i am interested in reading about what variator tuning ended up being optimal before i star purchasing the parts !

Is my best option to go for the Malossi 190 kit and the malossi secondary gear kit?

Cheers
J

Our LX is using the ET4 125 secondary with the polini primary and a 190 kit. I think this gearing is perfect for the 190. Top speed is 80mph and no issues at low speed either. I'm running the stock variator with 10g weights.

I never posted Part 5 because I really have never finished experimenting with the variator.

With much hindsight, I think I'd go Patrick's route with the secondary gearing from the Polini/125 combination if I had it to do over again. The Polini with the 150 secondary is just a tad too tall. Not bad, but not optimal.

Thank you for your replies - it does seem that the perfect 190m set up seems to be somewhat of a holy grail!!


When you say the Polinin primary gear are you referring to the

P2021389 - 17 - 44

and matching this with the

ET4/LX 125 - 15 - 42

Secondary?


Also interested in your drive oppsclunkthud! Have you changed anything on your clutch or changed your clutch completely?

I have already upgraded the springs to give me a better take off but think the malossi red are probably a bit too stiff for the stock engine - i am expecting this will be much better once cyllinder is at 190! Also are you using Dr Pulley 10g sliders or standard rollers?

Many thanks for all your help/advice!

Cheers
J

Correct, that is exactly the setup I have.

As for rollers I'm running the piaggio 10g rollers right now (standard for the LX 150) and they are almost perfect. Maybe a little bit heavy but not much. I recently ordered the 9.5 and 8.5 sliders to play with but I'm waiting for the next belt change to do that.

As for the clutch, mine is stock and is close enough for me not to bother changing it.

The must have tool for tuning the clutch and variator is a good tach. I have a tiny-tach that I tape on when tuning.

My set up: final = Polini + GT 15/41 + slightly taller tire. Stock variator + red springs in the clutch.

Agree on 10g rollers being pretty close, I've tried 9.4, 9.8, 10, and 10.2.

9.4 -- very "revvy" and lost a couple "tucked" mph up top.
9.8 -- pretty close, had these in the longest, slightly "revvy" and lower mpg. No loss up top.
10.2 -- have these in now, feel "torquier" like they're better using fat midrange of the 190. Great mid 40s roll-on but maybe a bit slower accel up top. Slightly better mpg vs 9.8s.
Gonna try 10.6 for data point but think it will be too much.

Red springs -- engage at ~5k. Tried these first and don't really see any reason to swap em out. My theory is the springs are cheap to manufacture so Malossi includes 3 sets in the kit to justify cost. Anyone that tries all 3 is gonna use the red.

For gearing up I have a 130/70 rear tyre, Malossi variator (14grollers) x Kevlar belt (about a 1mm thicker than standard) polini speed clutch for smooth engagement. 120km/h is alot more relaxed with the Malossi variator than standard and able to hold into head wind and slight uphill. I have seen 135km/h indicated.
No loss of acceleration and like a bull out of the gates.
I have a mate with a Scarabeo 200 and he will eventually get me on real long straights, but with the light frame of the Vespa it is king through the twisties. Of course this is all with an injected version with 190kit Malossi forcemaster 2 pm tuning pipe, dyno tuned etc etc..

@Jimscoot - WOW 14g rollers - is this on a 125 with 190 cylinder? Bluecloud is worried about going to 10.6 so that seems very heavy?


@Bluecloud - So you have changed out both gears - by GT i guess its from the GT 125 model and these fit straight in? I also went straight for the red springs and like the take off now even though the power is still a bit low.

I am going to continue searching and see if I can button down a confirmed best set up for the 190 cylinder. Maybe a fully tuned version with all the trick bits and then a mid point version where not everything has been changed out.

I like that some people are getting good results with some stock elements and not just chucking the kitchen sink at it

Anyone else have a different set up that is worlking well ??

Bluecloud is running a GT200 rear hub, not just a gear swap.

Keep in mind that he is running a Malossi variator. Different variators have different ramp profiles, so the weight that works in one will likely not be the best in another.

Thank you Silverstreak and OppsclunkThud for the clarification - so easy to get things wrong.

I think i am going to go for the following as a starting point ...

Malossi 190c Kit
Polini Primary Gear 17/44
Stock ET4 secondary Gear 15/42
Malossi red clutch springs
Malossi torsion spring
Sotck Variator with 10g rollers (has anyone tried Dr Pulley Sliders with a 190 set up?)


Any ideas why no-one goes for the Malossi secondary gear (16/42) which is made for the 190 cylinder ? Happy not to change both but just wondering what the reason would be!

Cheers
J

Forgot to ask - no -one has mentioned jetting - are you all on stock jets?

The Malossi secondary (16/42) sits in between the 125 (15/42) and the 150 (16/41) gearing. So it ends up being a small down-gear for the 150 and a small up-gear for the 125. As an example with stock 125 gearing you would hit the limiter at 68mph, with the malossi secondary you'd hit it at 72mph, and with 150 gearing you hit it at 74mph.

I really need to finish that gearing calculator.

Thanks again for clarifying OKT!

I understand the ratios but do those top speeds change with the cylinder kit. Will i still be limited to 68mph with the stock secondary gearing?

your current set-up (which seems to be optimum) only changes the primary gear and keeps the standard secondary does that mean better initial acceleration but the same top end?

the figures above were just dealing with the secondary to show why people don't bother with it.

With the Polini Primary (17/44), 125 secondary (15/42), and stock variator you'll hit the limiter at 80mph. That lets you tune for max HP RPM up to 70mph where the variator will max out. Then from 70-80 the power will be falling off as you go higher in speed.

I didn't rejet but have thought about trying a slightly larger main.

The Malossi variator will give a lower initial gear ratio and a slighter taller top end because it utilizes the entire face pulley and holds a more consistent RPM over the entire speed range. Another thing I noticed with the standard belt and variator that long sustained high speed especially with the 190 kit where there's more load, I would loose performance and my acceleration would become sluggish and less responsive. the Malossi X Kevlar belt doesn't suffer from heat stress and maintains performance after long wide open highway travel.
However I do prefer the standard belt with the Polini 6 roller in my 300

Just to be sure what i am hearing. Are we in agreement that an Lx can be modded to cruise at 65-68 mph? How durable are these mods?

I love my Lx 150 and a cruise of 65 to 68 for me would make it perfect. But didn't want to even consider it if I will just be opening the Visa repair tool box again and again.

Even though it's quick it's still a small frame and sustained high speeds can be a chore that's why I have the 300 for the long hauls.
It's very durable I've covered over 5000/km with the Malossi kit and it just seems to get better the more mileage I put on her. I could easily live with just the LX but my mate has a road bike and he was always leaving me behind..hence the upgrade? Everytime I get back on the LX it puts a huge grin on my face it's hard to pick just one.

Interesting. I get this too. And you blame the factory belt?

Nikasil vs iron sleeve = Malossi arguably superior to factory.

Kit's been available for what, nearly 10 years? Any reported failures?

I've seen this on every CVT I've ever been on.